Berlin, Germany to Helsinki is an approximately 5-hour flight. You can also do a combination of flight and ferry; or drive. The time zone difference moving from Central European Time to Eastern European Time is 1 hour. In August, daytime highs in Helsinki are 24°C, while nighttime lows are 13°C. Cap off your sightseeing on the 20th (Mon) early enough to travel to Hamina.

You can drive from Helsinki to Hamina in 2 hours. In August, daily temperatures in Hamina can reach 23°C, while at night they dip to 13°C. Wrap up your sightseeing by early afternoon on the 24th (Fri) to allow enough time to travel back home.